1. Match Rings and Bases: Virtually all modern rifles are either pre-drilled and tapped for scope bases or grooved for the appropriate mounting attachments, so the first step is simply to make sure that the mounting system you select is the proper fit for your rifle and that the rings are of the right diameter and height for properly positioning your scope. Certain types of scope rings fit only certain types of scope bases, so make sure the components match. Scope rings also come in different heights, which might cause confusion.